4l80e overdrive sprag failure
Thread Starter
Launching!
Joined: Jan 2008
Posts: 238
Likes: 0
From: AUSTRALIA
4l80e overdrive sprag failure recently my supercharged warhawk with et ls7 heads was being tuned on dyno , first run made 940 rwhp . due to diff pinion gears breaking we stopped second run. We then stripped down the trans an noticed the updated over run sprag has failed, the little springs have been sqashed in their little case. my understanding is the overrun gear only gets used in d for drive, on our dyno pull we had it in third gear overun should not ingage. also with the sprag failure our converter stall had changed from 4000 to like 5700on the dyno. Any thoughts would be appreciated.
FormerVendor
Joined: Oct 2006
Posts: 3,123
Likes: 3
From: D-F/W
Hello Hawk,
We talked on the phone recently regarding this issue.
The Overunning Clutch (sprag) in the 4L80E is applied in Manually selected 1,2,3 and off in 4 (or overdrive). It is not applied in any gear when the shift lever is in OD / 4. The Overunning clutch provides engine braking in 1,2 and 3 manually selected gear ranges.
So, that means that if your pull was made in manually selected 3 then indeed the overunning clutch would take the hit when the rear axle let go.
There is no replacement part that will withstand that sort of punishment at that power level that I am aware of. It is simply a matter of the part taking a significant shock when the axle let go. My recommendation would be to replace it in full confidence that it is the best part you can buy for the job.
I say build and and hit it!
Hope that helps,
g
We talked on the phone recently regarding this issue.
The Overunning Clutch (sprag) in the 4L80E is applied in Manually selected 1,2,3 and off in 4 (or overdrive). It is not applied in any gear when the shift lever is in OD / 4. The Overunning clutch provides engine braking in 1,2 and 3 manually selected gear ranges.
So, that means that if your pull was made in manually selected 3 then indeed the overunning clutch would take the hit when the rear axle let go.
There is no replacement part that will withstand that sort of punishment at that power level that I am aware of. It is simply a matter of the part taking a significant shock when the axle let go. My recommendation would be to replace it in full confidence that it is the best part you can buy for the job.
I say build and and hit it!
Hope that helps,
g
TECH Regular
Joined: Feb 2004
Posts: 439
Likes: 1
From: burbank ca
roller l think you will find that the input one way clutch is applied in all forward gears except 4th when it over runs. the springs being smashed is caused by power being applied on and off very quickly and vilantly. good luck
FormerVendor
Joined: Oct 2006
Posts: 3,123
Likes: 3
From: D-F/W
g
